a. Perimeter Noise Barriers - Noise barriers, positioned between construction equipment and receptors, must be used for all construction projects. Such barriers may be semi-permanent given the time and space requirements of the job site. They may be made of wood, plastic, Plexiglas, precast concrete or steel panels, or where work site space permits, natural materials, such as dirt piles or earthen berms.
b. Noise barriers shall be used to reduce noise affecting pedestrians. Being relatively tall and solid, noise barriers form an excellent perimeter and/or security fence around a job site in addition to reducing noise at street level. Greater noise attenuation occurs when barriers are placed as close as possible to the noise source.
c. When the work site is within 200 feet of a residential receptor, the responsible party that is required to use a work site perimeter noise barrier (or "construction fence") under DOB rules and regulations shall ensure that noise-resistant material fully lines the interior face (facing the work site) of the perimeter barrier, and shall ensure that:
1. the barrier breaks the line-of-sight between the noise source and indoor receptors within 200 feet and a maximum of 20 feet above grade level where practicable; however, said barrier's height shall not exceed 15 feet, including the balanced canted portion;
2. the barrier is made of a material sufficiently resistant to noise in accordance with subdivision e of this section; and
3. there are no leaks or gaps that will allow noise to pass through the barrier.
d. Noise Barrier Design Options.
1. Semi-permanent noise barriers are barriers that, due to their height, will require some form of anchoring system. Typically, semi-permanent barriers are intended for long term continuous use. Thus they are built out of materials suitable to withstand weather conditions for several years. Materials such as tongue and groove wooden timbers, vertical I-beam posts and lagging, or precast concrete panels, serve very well as semi-permanent noise barriers. Being anchored, semi-permanent barriers can easily extend to heights of 15 feet and must be in accordance with DOB and FDNY rules and regulations.
2. Where practicable, the responsible party shall build a pitched panel on top of the barrier in order to provide better shielding for multi-story receptor buildings, however care must be taken to avoid having the barrier tip over from unbalanced loading.
3. Alternative barriers may be utilized in accordance with site-specific conditions. For example, shipping container (Conex) boxes are likely already available to the responsible party. For example, where work site space permits, these container boxes or truck trailers may be positioned along the edge of the work site to form a semi-permanent noise barrier. These containers are typically 8 feet wide by 8 feet tall and can be double-stacked to form a noise barrier 16 feet in height. The gaps between and/or under container boxes shall be filled-in to avoid having noise flank around or under the container boxes.
4. There are also several product vendors that design and manufacture noise barrier materials and barrier systems. These special purpose products are available in various colors and materials including wood, plastic, Plexiglas, precast concrete or steel panels. They are available with or without anchoring systems, as needed.
e. Noise Barrier Specifications. Noise barriers shall be made of noise-resistant material sufficient to achieve a Sound Transmission Class (STC) rating of STC 30 or greater, based on sound transmission loss data taken according to ASTM Test Method E 90. Such a barrier can provide as much as a 10 dBA insertion loss providing it is positioned as close as possible to the noise source or to the receptors. To be at all effective, the barrier must be long and tall enough to completely block the line-of-sight between the noise source and the receptors. The gaps between adjacent panels must be filled-in to avoid having noise penetrate directly through the barrier.
(Amended City Record 3/15/2017, eff. 4/14/2017)